Promising evidence exists that data-based decision-making can result in improvements in student achievement [1], but studies, e.g. [2], show that many schools do not use data properly. Support in the use of data is urgently needed. This chapter focuses on the design of a professional development course in the use of data. In the first phase of the project, case studies were conducted in five participating countries (England, Germany, The Netherlands, Poland and Lithuania) to develop a common data use framework. In the next phase, in two schools in each of the countries, a data use needs assessment was conducted using a survey. Finally, a professional development course was developed and implemented. Results of each of the phases are discussed in this paper.